The invention relates to a welt for shoes having at least one fabric-coated side, and methods for making such a welt. The invention further relates to methods of manufacturing shoes using fabric-coated welts.
Traditionally, a leather welt has been stitched to a shoe upper, which was in turn attached to the shoe sole, for comfort and longevity of the shoe. Modern welts are frequently made of synthetic materials, although it is often desirable to preserve a leather-like appearance.
The separate welt is most commonly in the form of a vinyl (or other plastic) strip, which is stitched to the upper, and is cemented and/or stitched to the midsole and/or sole. The cement is usually applied in the form of a viscous liquid to the surface of the welt, which is then placed in contact with the midsole and/or sole to form a bond. A difficulty arises when cementing the plastic welt to certain types of midsoles and soles, in that it is difficult to achieve a high-stength bond between the welt and the midsole and/or sole. Furthermore, the liquid cement may be messy and difficult to apply without marring the surface of the shoe.
Another common shoe construction uses the xe2x80x9cblow solexe2x80x9d method. In this method, the welt is stitched to the upper of the shoe, and the welt and upper are clamped in a mold. A liquid polymer precursor such as urethane is then mixed with a catalyst and poured into another mold in the shape of a shoe sole, and the two molds are clamped together. Heat is generated by the interaction of the catalyst and the precursor to expand the polyurethane of the sole to xe2x80x9cblowxe2x80x9d the liquid into contact with the welt, bonding welt and sole together and curing the sole.
Unfortunately, the blow sole method of shoe construction has been found to produce an inadequate bond between the sole and welt of the shoe for prior art welts. It is an object of the present invention to provide a welt which can be used in either a blow sole or a traditional shoe compaction to produce a shoe which does not separate during normal use.
In one aspect, the invention comprises a composite welt to be used in the manufacture of shoes. The welt comprises a layer of fabric bonded to at least one surface of the welt which will be placed in contact with the sole of the shoe. The welt may comprise materials such as poly(vinyl chloride) (PVC), thermoplastic rubber, chlorinated polyethylene (CPA) or ethyl vinyl acetate (EVA). The fabric may be a polyester stitchbond, for example a six-ounce stitchbond.
In another aspect, the invention comprises a method for making shoe welts, in which a welt is extruded, and a strip of fabric is attached to a surface of the welt intended to be placed in contact with the sole of the shoe. The extruded welt may comprise a coextruded adhesive layer, which is used to attach the fabric to the welt. The fabric may be a polyester stitchbond, for example a six-ounce stitchbond.
In yet another aspect, the invention comprises a method for making shoes. The method comprises providing a polymer welt having a layer of fabric bonded to a surface of the welt, attaching the welt to an upper of a shoe, providing a mold for a shoe sole, filling the mold with a liquid sole precursor composition, placing the mold in contact with the welt, inducing the precursor to penetrate the fabric layer, and solidifying the precursor to form a solid sole attached to the welt. The welt may comprise materials such as PVC, thermoplastic rubber, CPE, or EVA. The fabric may be a polyester stitchbond, for example a six-ounce sntchbond, and may be attached to the welt, for example, by a coextruded adhesive layer. The welt may be stitched or glued to the upper. The sole may comprise polyurethane. Inducing the precursor to penetrate the fabric layer may include inducing a chemical reaction in the precursor, for example via a catalyst added to the precursor.
In still another aspect, the invention comprises a method for making shoes. The method comprises providing a polymer welt having a fabric layer bonded to a surface thereof, attaching the welt to an upper, and attaching a sole to the fabric layer. The sole may be attached to the fabric by an adhesive such as neoprene cement, urethane cement, or alpha-poly-alpha-ol efin (APAO), and may itself comprise materials such as, for example, neoprene, EVA, leather, leather board, stitchbond boards, or urethanes.